[thirdparty/kernel/stable.git] / mm / page_ext.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memblock.h>
#include <linux/page_ext.h>
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/kmemleak.h>
#include <linux/page_owner.h>
#include <linux/page_idle.h>

/*
 * struct page extension
 *
 * This is the feature to manage memory for extended data per page.
 *
 * Until now, we must modify struct page itself to store extra data per page.
 * This requires rebuilding the kernel and it is really time consuming process.
 * And, sometimes, rebuild is impossible due to third party module dependency.
 * At last, enlarging struct page could cause un-wanted system behaviour change.
 *
 * This feature is intended to overcome above mentioned problems. This feature
 * allocates memory for extended data per page in certain place rather than
 * the struct page itself. This memory can be accessed by the accessor
 * functions provided by this code. During the boot process, it checks whether
 * allocation of huge chunk of memory is needed or not. If not, it avoids
 * allocating memory at all. With this advantage, we can include this feature
 * into the kernel in default and can avoid rebuild and solve related problems.
 *
 * To help these things to work well, there are two callbacks for clients. One
 * is the need callback which is mandatory if user wants to avoid useless
 * memory allocation at boot-time. The other is optional, init callback, which
 * is used to do proper initialization after memory is allocated.
 *
 * The need callback is used to decide whether extended memory allocation is
 * needed or not. Sometimes users want to deactivate some features in this
 * boot and extra memory would be unneccessary. In this case, to avoid
 * allocating huge chunk of memory, each clients represent their need of
 * extra memory through the need callback. If one of the need callbacks
 * returns true, it means that someone needs extra memory so that
 * page extension core should allocates memory for page extension. If
 * none of need callbacks return true, memory isn't needed at all in this boot
 * and page extension core can skip to allocate memory. As result,
 * none of memory is wasted.
 *
 * When need callback returns true, page_ext checks if there is a request for
 * extra memory through size in struct page_ext_operations. If it is non-zero,
 * extra space is allocated for each page_ext entry and offset is returned to
 * user through offset in struct page_ext_operations.
 *
 * The init callback is used to do proper initialization after page extension
 * is completely initialized. In sparse memory system, extra memory is
 * allocated some time later than memmap is allocated. In other words, lifetime
 * of memory for page extension isn't same with memmap for struct page.
 * Therefore, clients can't store extra data until page extension is
 * initialized, even if pages are allocated and used freely. This could
 * cause inadequate state of extra data per page, so, to prevent it, client
 * can utilize this callback to initialize the state of it correctly.
 */

static struct page_ext_operations *page_ext_ops[] = {
#ifdef CONFIG_DEBUG_PAGEALLOC
	&debug_guardpage_ops,
#endif
#ifdef CONFIG_PAGE_OWNER
	&page_owner_ops,
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
	&page_idle_ops,
#endif
};

static unsigned long total_usage;
static unsigned long extra_mem;

static bool __init invoke_need_callbacks(void)
{
	int i;
	int entries = ARRAY_SIZE(page_ext_ops);
	bool need = false;

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
			page_ext_ops[i]->offset = sizeof(struct page_ext) +
						extra_mem;
			extra_mem += page_ext_ops[i]->size;
			need = true;
		}
	}

	return need;
}

static void __init invoke_init_callbacks(void)
{
	int i;
	int entries = ARRAY_SIZE(page_ext_ops);

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->init)
			page_ext_ops[i]->init();
	}
}

static unsigned long get_entry_size(void)
{
	return sizeof(struct page_ext) + extra_mem;
}

static inline struct page_ext *get_entry(void *base, unsigned long index)
{
	return base + get_entry_size() * index;
}

#if !defined(CONFIG_SPARSEMEM)


void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
{
	pgdat->node_page_ext = NULL;
}

struct page_ext *lookup_page_ext(const struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	unsigned long index;
	struct page_ext *base;

	base = NODE_DATA(page_to_nid(page))->node_page_ext;
	/*
	 * The sanity checks the page allocator does upon freeing a
	 * page can reach here before the page_ext arrays are
	 * allocated when feeding a range of pages to the allocator
	 * for the first time during bootup or memory hotplug.
	 */
	if (unlikely(!base))
		return NULL;
	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
					MAX_ORDER_NR_PAGES);
	return get_entry(base, index);
}

static int __init alloc_node_page_ext(int nid)
{
	struct page_ext *base;
	unsigned long table_size;
	unsigned long nr_pages;

	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	if (!nr_pages)
		return 0;

	/*
	 * Need extra space if node range is not aligned with
	 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
	 * checks buddy's status, range could be out of exact node range.
	 */
	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
		!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
		nr_pages += MAX_ORDER_NR_PAGES;

	table_size = get_entry_size() * nr_pages;

	base = memblock_alloc_try_nid(
			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
			MEMBLOCK_ALLOC_ACCESSIBLE, nid);
	if (!base)
		return -ENOMEM;
	NODE_DATA(nid)->node_page_ext = base;
	total_usage += table_size;
	return 0;
}

void __init page_ext_init_flatmem(void)
{

	int nid, fail;

	if (!invoke_need_callbacks())
		return;

	for_each_online_node(nid)  {
		fail = alloc_node_page_ext(nid);
		if (fail)
			goto fail;
	}
	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	invoke_init_callbacks();
	return;

fail:
	pr_crit("allocation of page_ext failed.\n");
	panic("Out of memory");
}

#else /* CONFIG_FLAT_NODE_MEM_MAP */

struct page_ext *lookup_page_ext(const struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	struct mem_section *section = __pfn_to_section(pfn);
	/*
	 * The sanity checks the page allocator does upon freeing a
	 * page can reach here before the page_ext arrays are
	 * allocated when feeding a range of pages to the allocator
	 * for the first time during bootup or memory hotplug.
	 */
	if (!section->page_ext)
		return NULL;
	return get_entry(section->page_ext, pfn);
}

static void *__meminit alloc_page_ext(size_t size, int nid)
{
	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
	void *addr = NULL;

	addr = alloc_pages_exact_nid(nid, size, flags);
	if (addr) {
		kmemleak_alloc(addr, size, 1, flags);
		return addr;
	}

	addr = vzalloc_node(size, nid);

	return addr;
}

static int __meminit init_section_page_ext(unsigned long pfn, int nid)
{
	struct mem_section *section;
	struct page_ext *base;
	unsigned long table_size;

	section = __pfn_to_section(pfn);

	if (section->page_ext)
		return 0;

	table_size = get_entry_size() * PAGES_PER_SECTION;
	base = alloc_page_ext(table_size, nid);

	/*
	 * The value stored in section->page_ext is (base - pfn)
	 * and it does not point to the memory block allocated above,
	 * causing kmemleak false positives.
	 */
	kmemleak_not_leak(base);

	if (!base) {
		pr_err("page ext allocation failure\n");
		return -ENOMEM;
	}

	/*
	 * The passed "pfn" may not be aligned to SECTION.  For the calculation
	 * we need to apply a mask.
	 */
	pfn &= PAGE_SECTION_MASK;
	section->page_ext = (void *)base - get_entry_size() * pfn;
	total_usage += table_size;
	return 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
static void free_page_ext(void *addr)
{
	if (is_vmalloc_addr(addr)) {
		vfree(addr);
	} else {
		struct page *page = virt_to_page(addr);
		size_t table_size;

		table_size = get_entry_size() * PAGES_PER_SECTION;

		BUG_ON(PageReserved(page));
		kmemleak_free(addr);
		free_pages_exact(addr, table_size);
	}
}

static void __free_page_ext(unsigned long pfn)
{
	struct mem_section *ms;
	struct page_ext *base;

	ms = __pfn_to_section(pfn);
	if (!ms || !ms->page_ext)
		return;
	base = get_entry(ms->page_ext, pfn);
	free_page_ext(base);
	ms->page_ext = NULL;
}

static int __meminit online_page_ext(unsigned long start_pfn,
				unsigned long nr_pages,
				int nid)
{
	unsigned long start, end, pfn;
	int fail = 0;

	start = SECTION_ALIGN_DOWN(start_pfn);
	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

	if (nid == NUMA_NO_NODE) {
		/*
		 * In this case, "nid" already exists and contains valid memory.
		 * "start_pfn" passed to us is a pfn which is an arg for
		 * online__pages(), and start_pfn should exist.
		 */
		nid = pfn_to_nid(start_pfn);
		VM_BUG_ON(!node_state(nid, N_ONLINE));
	}

	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
		if (!pfn_present(pfn))
			continue;
		fail = init_section_page_ext(pfn, nid);
	}
	if (!fail)
		return 0;

	/* rollback */
	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
		__free_page_ext(pfn);

	return -ENOMEM;
}

static int __meminit offline_page_ext(unsigned long start_pfn,
				unsigned long nr_pages, int nid)
{
	unsigned long start, end, pfn;

	start = SECTION_ALIGN_DOWN(start_pfn);
	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
		__free_page_ext(pfn);
	return 0;

}

static int __meminit page_ext_callback(struct notifier_block *self,
			       unsigned long action, void *arg)
{
	struct memory_notify *mn = arg;
	int ret = 0;

	switch (action) {
	case MEM_GOING_ONLINE:
		ret = online_page_ext(mn->start_pfn,
				   mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_OFFLINE:
		offline_page_ext(mn->start_pfn,
				mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_CANCEL_ONLINE:
		offline_page_ext(mn->start_pfn,
				mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_GOING_OFFLINE:
		break;
	case MEM_ONLINE:
	case MEM_CANCEL_OFFLINE:
		break;
	}

	return notifier_from_errno(ret);
}

#endif

void __init page_ext_init(void)
{
	unsigned long pfn;
	int nid;

	if (!invoke_need_callbacks())
		return;

	for_each_node_state(nid, N_MEMORY) {
		unsigned long start_pfn, end_pfn;

		start_pfn = node_start_pfn(nid);
		end_pfn = node_end_pfn(nid);
		/*
		 * start_pfn and end_pfn may not be aligned to SECTION and the
		 * page->flags of out of node pages are not initialized.  So we
		 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
		 */
		for (pfn = start_pfn; pfn < end_pfn;
			pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {

			if (!pfn_valid(pfn))
				continue;
			/*
			 * Nodes's pfns can be overlapping.
			 * We know some arch can have a nodes layout such as
			 * -------------pfn-------------->
			 * N0 | N1 | N2 | N0 | N1 | N2|....
			 */
			if (pfn_to_nid(pfn) != nid)
				continue;
			if (init_section_page_ext(pfn, nid))
				goto oom;
			cond_resched();
		}
	}
	hotplug_memory_notifier(page_ext_callback, 0);
	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	invoke_init_callbacks();
	return;

oom:
	panic("Out of memory");
}

void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
{
}

#endif
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
eefa864b JK	2	#include <linux/mm.h>
eefa864b JK	3	#include <linux/mmzone.h>
57c8a661	4	#include <linux/memblock.h>
eefa864b JK	5	#include <linux/page_ext.h>
	6	#include <linux/memory.h>
	7	#include <linux/vmalloc.h>
	8	#include <linux/kmemleak.h>
48c96a36	9	#include <linux/page_owner.h>
33c3fc71	10	#include <linux/page_idle.h>
eefa864b JK	11
	12	/*
	13	* struct page extension
	14	*
	15	* This is the feature to manage memory for extended data per page.
	16	*
	17	* Until now, we must modify struct page itself to store extra data per page.
	18	* This requires rebuilding the kernel and it is really time consuming process.
	19	* And, sometimes, rebuild is impossible due to third party module dependency.
	20	* At last, enlarging struct page could cause un-wanted system behaviour change.
	21	*
	22	* This feature is intended to overcome above mentioned problems. This feature
	23	* allocates memory for extended data per page in certain place rather than
	24	* the struct page itself. This memory can be accessed by the accessor
	25	* functions provided by this code. During the boot process, it checks whether
	26	* allocation of huge chunk of memory is needed or not. If not, it avoids
	27	* allocating memory at all. With this advantage, we can include this feature
	28	* into the kernel in default and can avoid rebuild and solve related problems.
	29	*
	30	* To help these things to work well, there are two callbacks for clients. One
	31	* is the need callback which is mandatory if user wants to avoid useless
	32	* memory allocation at boot-time. The other is optional, init callback, which
	33	* is used to do proper initialization after memory is allocated.
	34	*
	35	* The need callback is used to decide whether extended memory allocation is
	36	* needed or not. Sometimes users want to deactivate some features in this
	37	* boot and extra memory would be unneccessary. In this case, to avoid
	38	* allocating huge chunk of memory, each clients represent their need of
	39	* extra memory through the need callback. If one of the need callbacks
	40	* returns true, it means that someone needs extra memory so that
	41	* page extension core should allocates memory for page extension. If
	42	* none of need callbacks return true, memory isn't needed at all in this boot
	43	* and page extension core can skip to allocate memory. As result,
	44	* none of memory is wasted.
	45	*
980ac167 JK	46	* When need callback returns true, page_ext checks if there is a request for
	47	* extra memory through size in struct page_ext_operations. If it is non-zero,
	48	* extra space is allocated for each page_ext entry and offset is returned to
	49	* user through offset in struct page_ext_operations.
	50	*
eefa864b JK	51	* The init callback is used to do proper initialization after page extension
	52	* is completely initialized. In sparse memory system, extra memory is
	53	* allocated some time later than memmap is allocated. In other words, lifetime
	54	* of memory for page extension isn't same with memmap for struct page.
	55	* Therefore, clients can't store extra data until page extension is
	56	* initialized, even if pages are allocated and used freely. This could
	57	* cause inadequate state of extra data per page, so, to prevent it, client
	58	* can utilize this callback to initialize the state of it correctly.
	59	*/
	60
	61	static struct page_ext_operations *page_ext_ops[] = {
3a45acc0	62	#ifdef CONFIG_DEBUG_PAGEALLOC
e30825f1	63	&debug_guardpage_ops,
3a45acc0	64	#endif
48c96a36 JK	65	#ifdef CONFIG_PAGE_OWNER
	66	&page_owner_ops,
	67	#endif
33c3fc71 VD	68	#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
	69	&page_idle_ops,
	70	#endif
eefa864b JK	71	};
	72
	73	static unsigned long total_usage;
980ac167	74	static unsigned long extra_mem;
eefa864b JK	75
	76	static bool __init invoke_need_callbacks(void)
	77	{
	78	int i;
	79	int entries = ARRAY_SIZE(page_ext_ops);
980ac167	80	bool need = false;
eefa864b JK	81
eefa864b JK	82	for (i = 0; i < entries; i++) {
980ac167 JK	83	if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
	84	page_ext_ops[i]->offset = sizeof(struct page_ext) +
	85	extra_mem;
	86	extra_mem += page_ext_ops[i]->size;
	87	need = true;
	88	}
eefa864b JK	89	}
eefa864b JK	90
980ac167	91	return need;
eefa864b JK	92	}
	93
	94	static void __init invoke_init_callbacks(void)
	95	{
	96	int i;
	97	int entries = ARRAY_SIZE(page_ext_ops);
	98
	99	for (i = 0; i < entries; i++) {
	100	if (page_ext_ops[i]->init)
	101	page_ext_ops[i]->init();
	102	}
	103	}
	104
980ac167 JK	105	static unsigned long get_entry_size(void)
	106	{
	107	return sizeof(struct page_ext) + extra_mem;
	108	}
	109
	110	static inline struct page_ext get_entry(void base, unsigned long index)
	111	{
	112	return base + get_entry_size() * index;
	113	}
	114
eefa864b JK	115	#if !defined(CONFIG_SPARSEMEM)
	116
	117
	118	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	119	{
	120	pgdat->node_page_ext = NULL;
	121	}
	122
10ed6341	123	struct page_ext lookup_page_ext(const struct page page)
eefa864b JK	124	{
eefa864b JK	125	unsigned long pfn = page_to_pfn(page);
0b06bb3f	126	unsigned long index;
eefa864b JK	127	struct page_ext *base;
	128
	129	base = NODE_DATA(page_to_nid(page))->node_page_ext;
eefa864b JK	130	/*
	131	* The sanity checks the page allocator does upon freeing a
	132	* page can reach here before the page_ext arrays are
	133	* allocated when feeding a range of pages to the allocator
	134	* for the first time during bootup or memory hotplug.
	135	*/
	136	if (unlikely(!base))
	137	return NULL;
0b06bb3f	138	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
eefa864b	139	MAX_ORDER_NR_PAGES);
980ac167	140	return get_entry(base, index);
eefa864b JK	141	}
	142
	143	static int __init alloc_node_page_ext(int nid)
	144	{
	145	struct page_ext *base;
	146	unsigned long table_size;
	147	unsigned long nr_pages;
	148
	149	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	150	if (!nr_pages)
	151	return 0;
	152
	153	/*
	154	* Need extra space if node range is not aligned with
	155	* MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
	156	* checks buddy's status, range could be out of exact node range.
	157	*/
	158	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) \|\|
	159	!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
	160	nr_pages += MAX_ORDER_NR_PAGES;
	161
980ac167	162	table_size = get_entry_size() * nr_pages;
eefa864b	163
26fb3dae	164	base = memblock_alloc_try_nid(
eefa864b	165	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
97ad1087	166	MEMBLOCK_ALLOC_ACCESSIBLE, nid);
eefa864b JK	167	if (!base)
	168	return -ENOMEM;
	169	NODE_DATA(nid)->node_page_ext = base;
	170	total_usage += table_size;
	171	return 0;
	172	}
	173
	174	void __init page_ext_init_flatmem(void)
	175	{
	176
	177	int nid, fail;
	178
	179	if (!invoke_need_callbacks())
	180	return;
	181
	182	for_each_online_node(nid) {
	183	fail = alloc_node_page_ext(nid);
	184	if (fail)
	185	goto fail;
	186	}
	187	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	188	invoke_init_callbacks();
	189	return;
	190
	191	fail:
	192	pr_crit("allocation of page_ext failed.\n");
	193	panic("Out of memory");
	194	}
	195
	196	#else /* CONFIG_FLAT_NODE_MEM_MAP */
	197
10ed6341	198	struct page_ext lookup_page_ext(const struct page page)
eefa864b JK	199	{
	200	unsigned long pfn = page_to_pfn(page);
	201	struct mem_section *section = __pfn_to_section(pfn);
eefa864b JK	202	/*
	203	* The sanity checks the page allocator does upon freeing a
	204	* page can reach here before the page_ext arrays are
	205	* allocated when feeding a range of pages to the allocator
	206	* for the first time during bootup or memory hotplug.
	207	*/
	208	if (!section->page_ext)
	209	return NULL;
980ac167	210	return get_entry(section->page_ext, pfn);
eefa864b JK	211	}
	212
	213	static void *__meminit alloc_page_ext(size_t size, int nid)
	214	{
	215	gfp_t flags = GFP_KERNEL \| __GFP_ZERO \| __GFP_NOWARN;
	216	void *addr = NULL;
	217
	218	addr = alloc_pages_exact_nid(nid, size, flags);
	219	if (addr) {
	220	kmemleak_alloc(addr, size, 1, flags);
	221	return addr;
	222	}
	223
b95046b0	224	addr = vzalloc_node(size, nid);
eefa864b JK	225
	226	return addr;
	227	}
	228
	229	static int __meminit init_section_page_ext(unsigned long pfn, int nid)
	230	{
	231	struct mem_section *section;
	232	struct page_ext *base;
	233	unsigned long table_size;
	234
	235	section = __pfn_to_section(pfn);
	236
	237	if (section->page_ext)
	238	return 0;
	239
980ac167	240	table_size = get_entry_size() * PAGES_PER_SECTION;
eefa864b JK	241	base = alloc_page_ext(table_size, nid);
	242
	243	/*
	244	* The value stored in section->page_ext is (base - pfn)
	245	* and it does not point to the memory block allocated above,
	246	* causing kmemleak false positives.
	247	*/
	248	kmemleak_not_leak(base);
	249
	250	if (!base) {
	251	pr_err("page ext allocation failure\n");
	252	return -ENOMEM;
	253	}
	254
	255	/*
	256	* The passed "pfn" may not be aligned to SECTION. For the calculation
	257	* we need to apply a mask.
	258	*/
	259	pfn &= PAGE_SECTION_MASK;
980ac167	260	section->page_ext = (void )base - get_entry_size() pfn;
eefa864b JK	261	total_usage += table_size;
	262	return 0;
	263	}
	264	#ifdef CONFIG_MEMORY_HOTPLUG
	265	static void free_page_ext(void *addr)
	266	{
	267	if (is_vmalloc_addr(addr)) {
	268	vfree(addr);
	269	} else {
	270	struct page *page = virt_to_page(addr);
	271	size_t table_size;
	272
980ac167	273	table_size = get_entry_size() * PAGES_PER_SECTION;
eefa864b JK	274
eefa864b JK	275	BUG_ON(PageReserved(page));
0c815854	276	kmemleak_free(addr);
eefa864b JK	277	free_pages_exact(addr, table_size);
	278	}
	279	}
	280
	281	static void __free_page_ext(unsigned long pfn)
	282	{
	283	struct mem_section *ms;
	284	struct page_ext *base;
	285
	286	ms = __pfn_to_section(pfn);
	287	if (!ms \|\| !ms->page_ext)
	288	return;
980ac167	289	base = get_entry(ms->page_ext, pfn);
eefa864b JK	290	free_page_ext(base);
	291	ms->page_ext = NULL;
	292	}
	293
	294	static int __meminit online_page_ext(unsigned long start_pfn,
	295	unsigned long nr_pages,
	296	int nid)
	297	{
	298	unsigned long start, end, pfn;
	299	int fail = 0;
	300
	301	start = SECTION_ALIGN_DOWN(start_pfn);
	302	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	303
98fa15f3	304	if (nid == NUMA_NO_NODE) {
eefa864b JK	305	/*
	306	* In this case, "nid" already exists and contains valid memory.
	307	* "start_pfn" passed to us is a pfn which is an arg for
	308	* online__pages(), and start_pfn should exist.
	309	*/
	310	nid = pfn_to_nid(start_pfn);
	311	VM_BUG_ON(!node_state(nid, N_ONLINE));
	312	}
	313
	314	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
	315	if (!pfn_present(pfn))
	316	continue;
	317	fail = init_section_page_ext(pfn, nid);
	318	}
	319	if (!fail)
	320	return 0;
	321
	322	/* rollback */
	323	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	324	__free_page_ext(pfn);
	325
	326	return -ENOMEM;
	327	}
	328
	329	static int __meminit offline_page_ext(unsigned long start_pfn,
	330	unsigned long nr_pages, int nid)
	331	{
	332	unsigned long start, end, pfn;
	333
	334	start = SECTION_ALIGN_DOWN(start_pfn);
	335	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	336
	337	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	338	__free_page_ext(pfn);
	339	return 0;
	340
	341	}
	342
	343	static int __meminit page_ext_callback(struct notifier_block *self,
	344	unsigned long action, void *arg)
	345	{
	346	struct memory_notify *mn = arg;
	347	int ret = 0;
	348
	349	switch (action) {
	350	case MEM_GOING_ONLINE:
	351	ret = online_page_ext(mn->start_pfn,
	352	mn->nr_pages, mn->status_change_nid);
	353	break;
	354	case MEM_OFFLINE:
	355	offline_page_ext(mn->start_pfn,
	356	mn->nr_pages, mn->status_change_nid);
	357	break;
	358	case MEM_CANCEL_ONLINE:
	359	offline_page_ext(mn->start_pfn,
	360	mn->nr_pages, mn->status_change_nid);
	361	break;
	362	case MEM_GOING_OFFLINE:
	363	break;
	364	case MEM_ONLINE:
	365	case MEM_CANCEL_OFFLINE:
	366	break;
	367	}
	368
369	return notifier_from_errno(ret);
370	}
371
372	#endif
373
374	void __init page_ext_init(void)
375	{
376	unsigned long pfn;
377	int nid;
378
379	if (!invoke_need_callbacks())
380	return;
381
382	for_each_node_state(nid, N_MEMORY) {
383	unsigned long start_pfn, end_pfn;
384
385	start_pfn = node_start_pfn(nid);
386	end_pfn = node_end_pfn(nid);
387	/*
388	* start_pfn and end_pfn may not be aligned to SECTION and the
389	* page->flags of out of node pages are not initialized. So we
390	* scan [start_pfn, the biggest section's pfn < end_pfn) here.
391	*/
392	for (pfn = start_pfn; pfn < end_pfn;
393	pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
394
395	if (!pfn_valid(pfn))
396	continue;
397	/*
398	* Nodes's pfns can be overlapping.
399	* We know some arch can have a nodes layout such as
400	* -------------pfn-------------->
401	* N0 \| N1 \| N2 \| N0 \| N1 \| N2\|....
402	*/
2f1ee091	403	if (pfn_to_nid(pfn) != nid)
eefa864b JK	404	continue;
	405	if (init_section_page_ext(pfn, nid))
	406	goto oom;
0fc542b7	407	cond_resched();
eefa864b JK	408	}
	409	}
	410	hotplug_memory_notifier(page_ext_callback, 0);
	411	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	412	invoke_init_callbacks();
	413	return;
	414
	415	oom:
	416	panic("Out of memory");
	417	}
	418
	419	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	420	{
	421	}
	422
	423	#endif